Marital homicide committed by women occurs mainly in contexts of intimate gender violence, when they kill in order to survive attacks by their aggressors. This article presents a qualitative study carried out through the thematic content analysis of semi-structured interviews and the documentary analysis of the individual prison sentences of six Portuguese female prisoners convicted for the murder of their partners or former partners. The study explores the possible relationship between the practice of the crime and the exposure to a prior history of intimate gender violence, as well as problematizing their defence before the criminal justice system. Data obtained allowed us to recognize that all the women under study were victims of gender violence by their partners who they ultimately killed; that the initial period of separation of a couple constitutes an identical risk factor both for the practice of femicide and for the murder of offenders at the hands of their victims; and that there are inequities in the Portuguese criminal justice system regarding the conviction of these female prisoners that doubly punishes them in a penal system adapted to males, for having failed not only as citizens but as women.